Lesson 11.1.2

11.1.2 Nuclear fusion and fission Quiz: Pearson Edexcel Physics, Unit 11

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 11.1.2, Nuclear fusion and fission: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 11: Nuclear Radiation, written with Revision Ninja.

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The 20 questions

  1. What is nuclear fission?

    • The joining of two light nuclei into one heavier nucleus with less binding energy per nucleon.
    • The splitting of a heavy nucleus into two smaller nuclei, which releases energy.
    • The emission of an electron from a nucleus, with no change in its mass number at all.
    • The absorption of gamma rays by a nucleus, without changing its structure or charge.

  2. What is nuclear fusion?

    • The joining of light nuclei into a heavier nucleus, which releases energy.
    • The capture of an electron by a proton to form a neutron, which emits no energy.
    • The splitting of a heavy nucleus into lighter nuclei, with no energy released overall.
    • The emission of a beta particle from a light nucleus, with no change in mass number.

  3. Why are very high temperatures needed for nuclear fusion?

    • High temperature removes all protons from the nucleus, so fusion can then begin.
    • Nuclei need enough kinetic energy to overcome electrostatic repulsion.
    • High temperature makes nuclei lose their binding energy, so they split apart.
    • High temperature increases the mass of each nucleus, so they repel less strongly.

  4. Why are very high densities needed for fusion?

    • They cause nuclei to split rather than join.
    • They make the mass of the nuclei larger than the mass of the Sun.
    • They make collisions between nuclei frequent enough for fusion to occur.
    • They reduce the electrostatic repulsion between nuclei to zero.

  5. Which fuel is most commonly used in experimental fusion reactors?

    • Uranium-235 and plutonium-239
    • Deuterium and tritium
    • Helium-3 and lithium-6 only in the natural state
    • Carbon-14 and oxygen-16

  6. Which particle is released from a nucleus during alpha decay, and in which process is a neutron absorbed to start fission?

    • An alpha particle is released in alpha decay, and a neutron is absorbed by a heavy nucleus to start fission.
    • A gamma photon is released in fission, and an electron is absorbed to start fission.
    • A neutron is released in alpha decay, and an electron is absorbed to start fission.
    • A beta particle is released in fission, and a proton is absorbed to start fission.

  7. About 200 MeV is released per fission of uranium-235. How much energy is released by complete fission of 1.0 kg of uranium-235? Use 1 MeV = 1.6 x 10^-13 J.

    • about 8.2 x 10^10 J
    • about 8.2 x 10^13 J
    • about 1.6 x 10^16 J
    • about 2.0 x 10^12 J

  8. In deuterium-tritium fusion the reaction releases 17.6 MeV. Which product carries most of the kinetic energy?

    • The neutron, with about 14.1 MeV
    • The helium nucleus, with about 17.6 MeV
    • The neutron, with about 3.5 MeV
    • The helium nucleus, with about 14.1 MeV

  9. The binding energy per nucleon of iron-56 is about 8.8 MeV and of uranium-235 about 7.6 MeV. What energy per nucleon is released when uranium splits into nuclei near iron?

    • about 8.8 MeV
    • about 0.4 MeV
    • about 1.2 MeV
    • about 7.6 MeV

  10. Why does fusion of light nuclei release energy?

    • Fusion removes electrons, which releases their energy.
    • Light nuclei have negative binding energy, so combining them releases energy.
    • The product nucleus has less binding energy per nucleon than the light nuclei.
    • The binding energy per nucleon of the product is greater than that of the light nuclei that combined.

  11. A fission reactor produces 1.0 GW of electrical power at 33% efficiency. What is its thermal power?

    • 1.3 GW
    • 0.33 GW
    • 10 GW
    • 3.0 GW

  12. Why does fission produce radioactive waste?

    • Fission products are always stable and never emit radiation, so no waste is left.
    • Fission fragments are neutron-rich and unstable, so they decay radioactively.
    • Fission removes all neutrons from the reactor fuel, leaving a pure helium product.
    • Fission produces only helium, which is radioactive and must be stored for decades.

  13. Why must a fusion plasma be confined for a long time?

    • Plasma does not need confinement at all because it does not react with its container.
    • It must be held at high temperature and density long enough for net energy gain.
    • It must be cooled to absolute zero for the nuclei to fuse together without repelling.
    • It must be kept at low pressure so that the nuclei can separate and avoid collisions.

  14. Which factor makes fusion harder to achieve than fission in a reactor?

    • Fusion products are far more radioactive than fission products, which makes them harder to handle.
    • Fusion requires heavy nuclei, which are much harder to find in nature than light ones.
    • Fission needs a much hotter plasma than fusion does, so it is the harder process.
    • Nuclei must overcome strong electrostatic repulsion, needing very high temperature and density.

  15. A fusion reaction converts a small mass into energy. Which expression gives the energy from a mass defect Δ m?

    • E = Δ m / c^2
    • E = Δ m c
    • E = Δ m c^3
    • E = Δ m c^2

  16. Which reaction is an example of nuclear fission?

    • A nucleus emits an electron and an antineutrino, changing one neutron into a proton.
    • A heavy nucleus absorbs a neutron and splits into two lighter nuclei with more neutrons.
    • A nucleus emits a gamma photon with no change in its mass or its proton number at all.
    • Two light nuclei join together to form a heavier nucleus, releasing a neutron in the process.

  17. Which nuclei are the reactants in deuterium-tritium fusion?

    • Carbon-12 and oxygen-16
    • Deuterium (2/1 H) and tritium (3/1 H)
    • Uranium-235 and a neutron
    • Two helium-4 nuclei

  18. Why are control rods used in a fission reactor?

    • They increase the temperature of the reactor core so that the coolant boils more quickly.
    • They absorb neutrons so that on average one neutron per fission causes another fission.
    • They supply extra fuel so that the reaction never stops, even when the reactor is shut down.
    • They convert neutrons into protons, which reduces the radiation leaving the reactor core.

  19. Why does fission produce several neutrons?

    • Neutrons are produced only when fusion takes place.
    • Each neutron is converted into an electron during fission.
    • The released neutrons can cause further fissions, which can sustain a chain reaction.
    • Neutrons are produced because fission removes all the protons.

  20. On the binding energy per nucleon curve, what does fission of a heavy nucleus do?

    • It leaves the nucleons at the same point on the curve, releasing no energy.
    • It moves the nucleons towards the peak of the curve, releasing energy.
    • It moves the nucleons away from the peak, absorbing energy.
    • It moves the nucleons to the bottom of the curve, releasing energy.

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